 Abstract
During dire conditions, the
channelling of resources into
reproduction promotes species preservation. This strategy of survival through the next generation is
particularly important for plants that are unable to escape their environment
but can produce hardy seeds. The
onset of flowering in Arabidopsis is
genetically controlled by endogenous inputs that lead to de-repression of the
central floral integrators SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) and LEAFY (LFY). Environmental cues such as temperature,
day length, and light quality, converge to these genes for an integrated
flowering outcome. Although
environmental stresses profoundly impact flowering, the underlying molecular
mechanisms are not well defined.
Here we describe the role of the transcription factor OXIDATIVE STRESS 2
(OXS2) in maintaining vegetative growth, activating stress tolerance, or
entering into stress-induced reproduction. In the absence of stress, OXS2 is cytoplasmic and is needed
for vegetative growth; in its absence, the plant flowers early. Upon
stress, OXS2 is nuclear and is needed for stress tolerance; in its absence, the
plant is stress sensitive. OXS2
also has the capacity to activate its own promoter and those of floral
integrator genes, with direct binding to at least the SOC1 promoter. Stress-induced SOC1 expression and stress-induced flowering are impaired in mutants with
defects in OXS2 and three of the four OXS2-like paralogs. The ability
of OXS2 to autoactivate its own promoter may be an additional commensurate
response to the stress intensity, which could lead from a strategy based on
tolerating the effects of stress to one of escaping the stress via
reproduction.
We are currently writing on this work
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